Thesis (MScFoodSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

A computational investigation was performed to assess the effectiveness of Detached-Eddy Simulation (DES) as a tool for predicting icing effects. The AVUS code was employed to compute solutions for an iced wing configuration using DES and steady-state Reynolds Averaged Navier-Stokes (RANS) equation methodologies. The model wing was an extruded GLC305/944-ice shape section with a rectangular planform. Unstructured grids were generated using VGRID/GRIDTOOL. The one-equation Spalart-Allmaras turbulence model was used for all steady state RANS and DES computations. The numerical results were evaluated by comparison with experimental data. RANS solutions significantly under-predicted the lift and drag even after mesh refinement. The time-averaged DES computations showed some improvement in lift and drag coefficients, when compared to experimental data near stall at a 6 deg angle of attack. No significant improvement was observed at lower angles of attack. The DES computations were determined to be valid, since significant changes in the flow field were not observed after both mesh refinement and time step refinement.

The total worldwide base of installed wind energy peak capacity reached 94 GW by the end of 2007, including 1846 MW in Canada. Wind turbine systems are being installed throughout Canada and often in mountains and cold weather regions, due to their high wind energy potential. Harsh cold weather climates, involving turbulence, gusts, icing and lightning strikes in these regions, affect wind turbine performance. Ice accretion and irregular shedding during turbine operation lead to load imbalances, often causing the turbine to shut off. They create excessive turbine vibration and may change the natural frequency of blades as well as promote higher fatigue loads and increase the bending moment of blades. Icing also affects the tower structure by increasing stresses, due to increased loads from ice accretion. This can lead to structural failures, especially when coupled to strong wind loads. Icing also affects the reliability of anemometers, thereby leading to inaccurate wind speed measurements and resulting in resource estimation errors. Icing issues can directly impact personnel safety, due to falling and projected ice. It is therefore important to expand research on wind turbines operating in cold climate areas. This study presents an experimental investigation including three important fundamental aspects: 1) heat transfer characteristics of the airfoil with and without liquid water content (LWC) at varying angles of attack; 2) energy losses of wind energy while a wind turbine is operating under icing conditions; and 3) aerodynamic characteristics of an airfoil during a simulated icing event. A turbine scale model with curved 3-D blades and a DC generator is tested in a large refrigerated wind tunnel, where ice formation is simulated by spraying water droplets. A NACA 63421 airfoil is used to study the characteristics of aerodynamics and convective heat transfer. The current, voltage, rotation of the DC generator and temperature distribution along the airfoil, which are used to calculate heat transfer coefficients, are measured using a Data Acquisition (DAQ) system and recorded with LabVIEW software. The drag, lift and moment of the airfoil are measured by a force balance system to obtain the aerodynamics of an iced airfoil. This research also quantifies the power loss under various icing conditions. The data obtained can be used to valid numerical data method to predict heat transfer characteristics while wind turbine blades worked in cold climate regions. / October 2008

The total worldwide base of installed wind energy peak capacity reached 94 GW by the end of 2007, including 1846 MW in Canada. Wind turbine systems are being installed throughout Canada and often in mountains and cold weather regions, due to their high wind energy potential. Harsh cold weather climates, involving turbulence, gusts, icing and lightning strikes in these regions, affect wind turbine performance. Ice accretion and irregular shedding during turbine operation lead to load imbalances, often causing the turbine to shut off. They create excessive turbine vibration and may change the natural frequency of blades as well as promote higher fatigue loads and increase the bending moment of blades. Icing also affects the tower structure by increasing stresses, due to increased loads from ice accretion. This can lead to structural failures, especially when coupled to strong wind loads. Icing also affects the reliability of anemometers, thereby leading to inaccurate wind speed measurements and resulting in resource estimation errors. Icing issues can directly impact personnel safety, due to falling and projected ice. It is therefore important to expand research on wind turbines operating in cold climate areas. This study presents an experimental investigation including three important fundamental aspects: 1) heat transfer characteristics of the airfoil with and without liquid water content (LWC) at varying angles of attack; 2) energy losses of wind energy while a wind turbine is operating under icing conditions; and 3) aerodynamic characteristics of an airfoil during a simulated icing event. A turbine scale model with curved 3-D blades and a DC generator is tested in a large refrigerated wind tunnel, where ice formation is simulated by spraying water droplets. A NACA 63421 airfoil is used to study the characteristics of aerodynamics and convective heat transfer. The current, voltage, rotation of the DC generator and temperature distribution along the airfoil, which are used to calculate heat transfer coefficients, are measured using a Data Acquisition (DAQ) system and recorded with LabVIEW software. The drag, lift and moment of the airfoil are measured by a force balance system to obtain the aerodynamics of an iced airfoil. This research also quantifies the power loss under various icing conditions. The data obtained can be used to valid numerical data method to predict heat transfer characteristics while wind turbine blades worked in cold climate regions.

The total worldwide base of installed wind energy peak capacity reached 94 GW by the end of 2007, including 1846 MW in Canada. Wind turbine systems are being installed throughout Canada and often in mountains and cold weather regions, due to their high wind energy potential. Harsh cold weather climates, involving turbulence, gusts, icing and lightning strikes in these regions, affect wind turbine performance. Ice accretion and irregular shedding during turbine operation lead to load imbalances, often causing the turbine to shut off. They create excessive turbine vibration and may change the natural frequency of blades as well as promote higher fatigue loads and increase the bending moment of blades. Icing also affects the tower structure by increasing stresses, due to increased loads from ice accretion. This can lead to structural failures, especially when coupled to strong wind loads. Icing also affects the reliability of anemometers, thereby leading to inaccurate wind speed measurements and resulting in resource estimation errors. Icing issues can directly impact personnel safety, due to falling and projected ice. It is therefore important to expand research on wind turbines operating in cold climate areas. This study presents an experimental investigation including three important fundamental aspects: 1) heat transfer characteristics of the airfoil with and without liquid water content (LWC) at varying angles of attack; 2) energy losses of wind energy while a wind turbine is operating under icing conditions; and 3) aerodynamic characteristics of an airfoil during a simulated icing event. A turbine scale model with curved 3-D blades and a DC generator is tested in a large refrigerated wind tunnel, where ice formation is simulated by spraying water droplets. A NACA 63421 airfoil is used to study the characteristics of aerodynamics and convective heat transfer. The current, voltage, rotation of the DC generator and temperature distribution along the airfoil, which are used to calculate heat transfer coefficients, are measured using a Data Acquisition (DAQ) system and recorded with LabVIEW software. The drag, lift and moment of the airfoil are measured by a force balance system to obtain the aerodynamics of an iced airfoil. This research also quantifies the power loss under various icing conditions. The data obtained can be used to valid numerical data method to predict heat transfer characteristics while wind turbine blades worked in cold climate regions.

Thesis (MSc Food Sc) (Food Science)--Stellenbosch University, 2008. / The change in aspalathin, iso-orientin, orientin and total polyphenol (TP) content of a commercially produced fermented rooibos (FR) extract was monitored throughout production. Particular attention was paid to the effect of spray-drying on FR and unfermented rooibos (UR) extracts. The quality of commercial, South African rooibos iced teas made with FR extract was also investigated with respect to the aforementioned parameters. Subsequently, the effect of heating and storage on the phenolic composition and colour of experimental iced teas containing respectively FR, UR and nano emulsified unfermented rooibos (NEUR) extracts was investigated. The combined effect of pH (pH 3-7) and storage (5, 30 and 40ºC), as well as high (660 mg/L, 0-7 days at 30ºC; UR only) and low (0.5 mg/L) concentrations of H2O2, was determined on reconstituted FR, UR and NEUR extracts. Finally, eight rooibos iced teas (four variants; unflavoured and lemon-flavoured) were analysed for plant-like, hay-like, rooibos and lemon flavour, as well as astringency, using descriptive sensory analysis. The degree of consumer preference of the flavoured variants was determined using the nine point hedonic scale. In all cases, changes in individual flavonoid content were quantified using HPLC. The TP content of the iced teas and commercial extracts was determined using the Folin-Ciocalteu assay. Browning of the iced teas and reconstituted extracts was monitored spectrophotometrically (420 nm). Aspalathin, iso-orientin and orientin were found to be present after all stages of the FR extract production process. Spray-drying, specifically, also did not reduce the content of these flavonoids, or the TP content, in FR and UR extracts. Despite the relatively good retention during the heating and storage of experimental rooibos iced teas, these flavonoids were either absent or present at extremely low levels in commercial iced teas. The latter suggested that either extremely low quantities of extract, no extract at all or extracts of poor quality, were used for the production of the analysed iced teas. Increased degradation was generally observed for sterilisation treatments compared to pasteurisation whilst losses during storage increased with time. The presence of citric acid, due to its pH-lowering effect, and ascorbic acid, due to its antioxidant activity, was integral to the retention of aspalathin, iso-orientin and orientin during heating, but less so during storage. The UR iced teas generally performed better than their FR counterparts, however, NEUR iced teas exhibited the greatest retention of the aforementioned flavonoids. Heating and storage resulted in browning of most iced teas, whilst the TP content increased slightly or remained unchanged. Phenolic retention in FR and UR extracts decreased with increasing pH and temperature, with concomitant browning. However, between pH 5 and 7, the stability of aspalathin was superior in the NEUR extract formulation. The latter also greatly resisted absorbance changes at pH 3 and 4, despite a loss of aspalathin. The phenolic content of UR extract was immediately reduced by high a concentration of H2O2, however, no significant (P≥0.05) changes in absorbance were detected, suggesting the formation of intermediate, colourless oxidation products. Formulations containing ascorbic acid experienced the greatest reductions. This was attributed to the iron reducing ability of this compound, as reduced iron accelerates the rate of the Fenton reaction. At low levels of H2O2, only the FR extract exhibited a loss of phenolic compounds. The level of iron in this extract was the highest. Despite having the greatest aspalathin and total flavonoid content, lemon flavoured unfermented rooibos iced tea (UF/LEMON) was disliked by consumers. Preference was directed away from the plant-like characteristic of this tea and towards rooibos flavour, characteristic of fermented rooibos iced tea. Iced tea comprising both FR and NEUR extract produced a product that 77% of consumers rated positively. Its slight hay-like flavour did not significantly (P≥0.05) reduce the liking of this product compared to fermented rooibos iced tea.

This research is mainly focused on the development of the adaptive Cartesian grid methods for compressibl  e flow. At first, the ghost cell method and its applications for inviscid compressible flow on adaptive tree Cartesian grid are developed. The proposed method is successfully used to evaluate various inviscid compressible flows around complex bodies. The mass conservation of the method is also studied by numerical analysis. The extension to three-dimensional flow is presented. Then, an h-adaptive Runge–Kutta discontinuous Galerkin (RKDG) method is presented in detail for the development of high accuracy numerical method under Cartesian grid. This method combined with the ghost cell immersed boundary method is also validated by well documented test problems involving both steady and unsteady compressible flows over complex bodies in a wide range of Mach numbers. In addition, in order to suppress the failure of preserving positivity of density or pressure, which may cause blow-ups of the high order numerical algorithms, a positivity-preserving limiter technique coupled with h-adaptive RKDG method is developed. Such a method has been successfully implemented to study flows with the large Mach number, strong shock/obstacle interactions and shock diffraction. The extension of the method to viscous flow under the adaptive Cartesian grid with hybrid overlapping bodyfitted grid is developed. The method is validated by benchmark problems and has been successfully implemented to study airfoil with ice accretion. Finally, based on an open source code, the detached eddy simulation (DES) is developed for massive separation flow, and it is used to perform the research on aerodynamic performance analysis over the wing with ice accretion.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2012-05-04T22:22:58Z No. of bitstreams: 2 Dissertacao_ConsolidacaoFormacaoProfessor.pdf: 1565572 bytes, checksum: d8f79e38a691265e108415d5dd09c409 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Edisangela Bastos(edisangela@ufpa.br) on 2012-05-04T22:23:07Z (GMT) No. of bitstreams: 2 Dissertacao_ConsolidacaoFormacaoProfessor.pdf: 1565572 bytes, checksum: d8f79e38a691265e108415d5dd09c409 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2012-05-04T22:23:07Z (GMT). No. of bitstreams: 2 Dissertacao_ConsolidacaoFormacaoProfessor.pdf: 1565572 bytes, checksum: d8f79e38a691265e108415d5dd09c409 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2010 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo cujo tema perpassa o campo da Educação Superior teve a tarefa de dissertar sobre o objeto a consolidação da formação do professor-pesquisador da Pós-Graduação em Educação da UFPA, que traduziu uma inquietação epistemológica em compreender a ação educativa desenvolvida no espaço pós-graduado e que atualmente vem se desenvolvendo pela relação entre pesquisa-trabalho-produtividade que encontra suas raízes ainda na gênese da Pós-Graduação no Brasil na década de 60. O objetivo geral foi analisar o trabalho docente do professor-pesquisador da Pós-Graduação em Educação da Universidade Federal do Pará – UFPA, a partir do processo de consolidação da sua formação pós-graduada, e os específicos que incidiram nos cinco capítulos da Dissertação, a saber: identificar os aspectos legais e epistemológicos que dão voz ao trabalho docente no Ensino Superior tendo como elo o conceito de professor-pesquisador; verificar os dispositivos institucionais que regulam o trabalho docente na Pós-Graduação; analisar o processo de consolidação da formação dos professores-pesquisadores da Pós-Graduação em Educação da UFPA; examinar o nível de produtividade científica dos professores-pesquisadores da Pós-Graduação em Educação da UFPA e; observar como o trabalho docente desses pesquisadores vem sendo avaliado pela Comissão Externa de Avaliação da CAPES. Dedicando-se a seguinte problematização: Como o trabalho do professor-pesquisador se constitui após o processo de consolidação da sua formação pós-graduada? A qual desencadeou as questões-problemas discutidas em cada capítulo: De que modo o trabalho docente desenvolvido no Ensino Superior vem se caracterizando dentro da abordagem epistemológica que envolve o conceito de professor-pesquisador? Em que medida os aspectos institucionais configuram a atividade docente desenvolvida na Pós-Graduação, particularmente no Instituto de Ciências da Educação da UFPA? O que revela a introdução das teses de doutoramento dos professores-pesquisadores? Como a produtividade científica desses professores-pesquisadores vem se constituindo dentro do Currículo Lattes? Como a CAPES avaliou o trabalho docente na Pós-Graduação em Educação da UFPA no lapso temporal de 2003 a 2010? Dada as questões, o estudo foi construído sob uma abordagem teórico-metodológica ancorada no enfoque histórico-educativo, neste momento autores como Carvalho (2003) e Lombardi (2004) compuseram o diálogo necessário para justificar a opção que desencadeou também na escolha das cinco fontes históricas examinadas no estudo, as bibliográficas sobre a epistemologia do professor-pesquisador, as prescrições oficiais, as introduções das teses de Doutorado do atual corpo docente do PPGED da UFPA, os currículos lattes desses sujeitos e por último, as fichas de avaliação da CAPES aplicadas ao PPGED nos anos de 2004 e 2007 referentes à avaliação trienal coordenada pelo Órgão. Tratou-se de um estudo de caso instrumental interessado em compreender a ação educativa no espaço pós-graduado, tendo como lapso temporal os anos de 2003 a 2010. Dentre os resultados alcançados, concluiu-se, principalmente, que a consolidação do professor-pesquisador tem na etapa de conclusão do Doutorado a consolidação da formação pós-graduada, logo do ponto de partida, uma vez que é na experiência construída no trabalho docente, no ambiente pós-graduado em seu contato com os diferentes processos investigativos que cercam esse campo de significados e contradições que o professor consolida de fato sua atividade investigativa. / This study theme running through the field of higher education had the task to speak about the object the consolidation of teacher-researcher at the Graduate Education of UFPA, which reflected an epistemological concern in understanding the educational actions developed in the post- graduate and currently is developing the relationship between labor-productivity research that finds its roots still in the genesis of the Graduate Program in Brazil in the 60s. The overall objective was to analyze the teaching of the teacher-researcher at Graduate Education, Federal University of Pará - UFPA, from the consolidation of its post-graduate training, and focused on five specific chapters of the dissertation, namely: to identify the legal and epistemological giving voice to teaching in Higher Education as a link with the concept of teacher-researcher checking of institutional arrangements that govern the teaching work at the Graduate; analyze the consolidation process of the formation of teacher-researchers of Graduate Education, UFPA; examine the level of scientific productivity of teachers and researchers of Graduate Education and UFPA; see how the teaching work of these researchers has been evaluated by the External Evaluation Commission of CAPES. Dedicating to the following problematic: As the work of the teacher-researcher is created after the consolidation of its post-graduate training? The issues which triggered the problems discussed in each chapter: How does the teacher work developed in higher education has been characterized within the epistemological approach that involves the concept of teacher-researcher? To what extent the institutional aspects shape the teaching activities developed in the Graduate, particularly at the Institute of Education Sciences UFPA? This reveals the introduction of the PhD thesis of teacher-researchers? As the scientific productivity of these teacher-researchers has been developing within the Lattes? As the CAPES evaluated the teaching in the Graduate Education of the UFPA time gap from 2003 to 2010? Given the issues, the study was built on a theoretical and methodological approach grounded in historical and educational, this time authors as Carvalho (2003) and Lombardi (2004) made up the dialogue necessary to explain what triggered the option in the choice of the five sources examined in the historical study, literature on the epistemology of the teacher-researcher, requirements officers, issues of doctoral theses of the current faculty PPGED UFPA, lattes curricula of these subjects and finally the evaluation sheets from CAPES apply PPGED to the years 2004 and 2007 concerning the triennial evaluation coordinated by the Authority. Was an instrumental case study concerned with understanding the educational activity in the post-graduate, considered the delay of 2003-2010. Among the results, it was found mainly to the consolidation of the teacher-researcher is in the stage of completion of the consolidation of PhD postgraduate training, just the starting point, since it is built on experience in the teaching, in the post-graduate degree in their contact with the various investigative processes that surround this field of meanings and contradictions that the teacher actually consolidates its investigative activity.

Eskom makes a significant contribution to social and economic development in South Africa, which is realised through its corporate social investment policy. Eskom could reinforce its contribution by adopting Integrated Community Economic Development (ICED), which addresses issues of poverty in a holistic way. Nthomang and Rankopo (1997:209) regard (ICED) as “...a holistic approach that seeks to address socio-political constraints preventing marginalised communities from attaining humane standards of living”. The goal of the study was to explore the views held by corporate social investment practitioners’ on Eskom’s contribution to socio-economic projects within a sustainable framework to alleviate poverty and unemployment. The research followed a qualitative approach, and data was gathered by means of semi-structured interviews. Participants in the study came from four regions, the Central, Southern, Northern regions and part of the North Western region of Eskom’s terrain. From the key findings, it was evident that Eskom contributes to the social and economic development of communities, but its contribution could be more effective and meaningful if funding policies, partnership involvement, the role played by corporate social investment practitioners’ and community economic development strategies were more closely aligned with an Integrated Community Economic Development approach. The study concluded that the Solertia Institute Model Program for the advancement of capable communities provided a relevant framework that could be adapted as a viable strategy whereby Eskom could contribute to sustainable Integrated Social and Economic Development. The researcher recommends that the Eskom management adopt the proposed strategy as part of Eskom’s corporate social investment policy. Further, the implementation of the respective projects should be aligned with the phases of the Solertia Institute Model Program. Projects should therefore be continuously monitored to assess and evaluate Eskom’s contribution to sustainable Integrated Community Economic Development. Copyright / Dissertation (MSW)--University of Pretoria, 2012. / Social Work and Criminology / unrestricted

Community Economic Development (CED) in South Africa is shaped by the historicalprocesses of the former Apartheid regime that discriminated the social and economic rights of the majority of people, thus disempowering them to participate in development. The notion of Integrated Community Economic Development (ICED) enhances the concept of participation in community economic development in that it advocates for an empowerment dimension in development. In order to facilitate this participation, the government has introduced the participatory mechanisms of the IDP and ward committee system. Paradoxically, inequalities in development persist in previously disadvantaged homelands which were excluded from participation in developmental initiatives of the former regime. Consequently, these mechanisms for ICED have not been able to achieve participation of communities in ICED. Winterveldt is one such area with a legacy of social exclusion through racial and ethnic discrimination. The goal of the study was to explore the lack of participation of the Winterveldt community in ICED guided by the research question: “What are the reasons for the lack of participation of the Winterveldt community in ICED?” A qualitative research approach was followed and the research design was a case study. Data was gathered through focus group interviews and document studies. The focus groups were comprised of 13 community participants and 10 ward committee personnel from Winterveldt. Research findings revealed various reasons for the lack of participation in the ICED of Winterveldt including role confusion, the lack of information and training on the IDP and political power abuse. The study concluded that participation flows along lines that safeguard the interests of local government with little respect for the community’s capacity to make decisions concerning their development. Recommendations towards the achievement of participation in the ICED of Winterveldt include training on the Integrated Development Plan (IDP), the development of a guideline for implementing the IDP and changes in attitudes of all actors in the ICED of Winterveldt. Copyright / Dissertation (MSW)--University of Pretoria, 2012. / Social Work and Criminology / unrestricted